English verb conjugation
MUST RUFF

Regular verb: ruff - ruffed - ruffed

Affirmation

Simple form	V-ing form
I must ruff you must ruff she must ruff we must ruff you must ruff they must ruff	I must be ruffing you must be ruffing she must be ruffing we must be ruffing you must be ruffing they must be ruffing
Perfect	V-ing perfect
I must have ruffed you must have ruffed she must have ruffed we must have ruffed you must have ruffed they must have ruffed	I must have been ruffing you must have been ruffing she must have been ruffing we must have been ruffing you must have been ruffing they must have been ruffing

Negation

Simple form	V-ing form
I must not ruff you must not ruff she must not ruff we must not ruff you must not ruff they must not ruff	I must not be ruffing you must not be ruffing she must not be ruffing we must not be ruffing you must not be ruffing they must not be ruffing
Perfect	V-ing perfect
I must not have ruffed you must not have ruffed she must not have ruffed we must not have ruffed you must not have ruffed they must not have ruffed	I must not have been ruffing you must not have been ruffing she must not have been ruffing we must not have been ruffing you must not have been ruffing they must not have been ruffing

Interrogative form

Simple form	V-ing form
must I ruff? must you ruff? must she ruff? must we ruff? must you ruff? must they ruff?	must I be ruffing? must you be ruffing? must she be ruffing? must we be ruffing? must you be ruffing? must they be ruffing?
Perfect	V-ing perfect
must I have ruffed? must you have ruffed? must she have ruffed? must we have ruffed? must you have ruffed? must they have ruffed?	must I have been ruffing? must you have been ruffing? must she have been ruffing? must we have been ruffing? must you have been ruffing? must they have been ruffing?

Interro-negative form

Simple form	V-ing form
must I not ruff? must you not ruff? must she not ruff? must we not ruff? must you not ruff? must they not ruff?	must I not be ruffing? must you not be ruffing? must she not be ruffing? must we not be ruffing? must you not be ruffing? must they not be ruffing?
Perfect	V-ing perfect
must I not have ruffed? must you not have ruffed? must she not have ruffed? must we not have ruffed? must you not have ruffed? must they not have ruffed?	must I not have been ruffing? must you not have been ruffing? must she not have been ruffing? must we not have been ruffing? must you not have been ruffing? must they not have been ruffing?